If those were captured in the camera, you may not have any good options. First be sure that you have all the codec and frame-rate settings absolutely correct. With luck, you set something wrong during import or render.
I have no Vegas expertise, but I have seen banding from LED lights repaired on other platforms thru a pains-taking combination of keying and the use of the "limit color" selection tools in color correction to make the darker bands the same color as the background and soften them. The bands were much wider and softer to start with in those instances, though.
You've played with the "rolling shutter" correction plug-ins?